The following is a tabulation of some prior art that appears relevant:
U.S. PatentsPat. No.Kind CodeIssue DatePatentee9,021,719B22015 May 5Rabushka3,875,8881975 Apr. 8McNaughton1,331,952A1920 Feb. 24Brant8,272,146B12012 Sep. 25JacksonU.S. patent application PublicationsPublication Nr.Kind CodePubl. DateApplicant20060086006A12006 Apr. 27ForrestForeign Patent DocumentsForeign Doc. Nr.Cntry CodeKind CodeApp or Patentee0284070EPA2Giljohann
Spring action footwear is an amalgam of various fields. On one end of the spectrum, shock cushioning technology provides shock absorption for runners and skiers, and on the other end, it offers propulsion, allowing the user to literally bounce pogo stick style. Mild shock absorption usually relies on elastics sandwiched between semi-rigid platforms. Rabushka, U.S. Pat. No. 9,021,719 B2 discloses semi-rigid inner and outer soles situated in a see-saw configuration, the outsole providing a mid-point fulcrum, with elastic filler in the heel and toe regions. Greater shock absorption is provided by springs, which are used when the movement involves heightened impact, such as in skiing. Giljohann, EP 0284070 A2 discloses a ski boot with a series of vertical springs compressed between the boot's inner and outer soles. Forrest, U.S. Pat. App. No. US 2006/0086006 A1, uses strategically positioned, cylinder style shock absorbers, in an exoskeleton surrounding a ski boot. Then there is bouncing footwear, which not only cushions impact, it adds substantial rebound energy, enough to propel the wearer off the ground. Brant, U.S. Pat. No. 1,331,952 and McNaughton, U.S. Pat. No. 3,875,688 disclose a shoe with a single, large spring connected to the sole. Jackson, U.S. Pat. No. 8,272,146 B1, discloses multiple hydraulic springs sandwiched between a shoe and surface platform.